Please keep in mind and give me baby steps ( I am not planning on rushing it I just want to do it right little by little ). I have experience with freshwater setup and have a few common fish some include ( black moores, clown loach , a few tetras , red tail shark. ).

So far I have

1)The tank itself + the stand
2)I bought Tetra EX70 Whisper Filter today ( I bought it from the store but I found it 30$ cheaper online so will be returning it please tell me if it would be fine on a saltwater).
3)I also bought a big bucket of Instant Ocean Synthetic Sea Salt .
4)I have about 80lbs of gravel ( small ones not powder but the size of peanuts).
5) I also bought de-chlorinator.
6)Hydrometer.

Fish I am planning once the tank is properly set up and cycled.

1) Lion fish ( I am planning on feeding it live gold fish, not anything frozen ).
2) Porcupine puffer
3) A few clown fish ( the oscillaris, forgive my spelling but its the same one that looks like nemo )
4) one or two small-med sized tangs

Thats it so far ( I will be adding more species in the future once I gain more knowledge on saltwater fish).

My questions are as follows, and yes I have read about 30 different links on setting up saltwater aquariums and I am still confused.

1)Do I need live sand and crushed corals ( substrate ) or can I make the gravel work? ( I can get pictures if needed ).
2)Are corals a necessity for a saltwater setup? I know they are expensive and so is this hobby but I want to atleast get the aquarium running for now.
3) I have read on some sites that you do not need a filter as long as you have protein skimmer and some live rock. is that true or I do need a filter?
4) If so what kind of filter? UGF or RUGF?

Please comment and I don't mind if its good or bad, I am here to gain knowledge and am expecting criticism.

Alright I'll help you out with one of your questions. Coral are by no means necessary to maintain a thriving saltwater tank. What you're looking at keeping is a FOWLR tank, Fish-Only-With-Live-Rock.

Your stocking list needs some fixing up. First off is the lionfish. I wouldn't recommend feeing it goldfish. Think about it. Lionfish are saltwater fish. Goldfish are freshwater fish. A freshwater fish won't have all of the necessary nutrients that a lionfish needs to survive. While lots of people do in fact feed their predators goldfish, it's not recommended. You would be better off trying to feed it something like White Shrimp http://www.liveaquaria.com/product/prod_display.cfm?c=830+2190+2191&pcatid=2191 and eventually switching it to frozen foods. Also keep in mind that predators, like the lion, produce a lot more waste than non-predators. You would need a really good protein skimmer to keep your chemical levels in check.

The Porcupine Puffer is too big for a 75 gallon.

You can't keep "a few" clowns together because eventually they'll pair off and start killing each other for territory until only one pair remains. You can keep one single clown or a pair. Also, since you didn't specify what species of lion you wish to keep, your clowns might become dinner if they are too small.

A 75 gallon is tight for any species of tangs, but it can be done. The tang will probably be pretty territorial and attack other fish as it gets larger. You might be able to get away with a Kole Tang or Tomini Tang since they are the smaller species of tang and they are also less aggressive than other tangs, but it's still pretty risky. Be prepared to go fishing should the tang be too much for your other fish to handle. Do not mix two tangs together in a tank this size. One will wind up dead.

I appreciate your feedback very much ( I have read it all over twice ). One this is for certain, I am not ready to become a saltwater hobbist right now. I am going to be switching the tank ( its empty as of now ) to a freshwater setup as of today. I have much more to learn and once I can get my hands on a decent priced tank over 100 gal, I will decide to go saltwater. I know it will be a learning experience.

I will definately buy the book and gain some knowldege on the saltwater world!
Thanks for not bashing me for being new and helping me out.
Have a great one
Jesse

Jesse, only you can make that decision but if you already have kept FW then a SW tank can be yours---the 75 is a great size and it's not all that more difficult if you set up a basic marine fish system (with the right species) and avoid the inverts for a while. I had great success as a teenager with not much more than basic equipment like undergravel filters and a couple of good books. The book that Mike is pointing you to is an excellent choice.

Also please take a few minutes and read my two articles here when you decide to move forward...